1. Field of the Invention
The present invention relates to sheet feeders for feeding sheets such as recording media and documents, image-forming apparatuses including the sheet feeders, and image-reading apparatuses including the sheet feeders.
2. Description of the Related Art
Image-forming apparatuses for recording an image on a recording medium and image-reading apparatuses for reading an image from a document include a sheet feeder for feeding a sheet such as a recording medium or a document to, for example, an image-forming unit or a reading unit. Examples of image-forming apparatuses (or recording apparatuses) include printers, copiers, printing machines, fax machines, and multifunction devices and systems having such functions. Examples of image-reading apparatuses include scanners and multifunction devices and systems having a scanner function. In the present application, the term “image” should be broadly interpreted, including characters, symbols, lines, and patterns.
Typical sheet feeders for use in, for example, image-forming apparatuses and image-reading apparatuses feed a sheet in a direction parallel to the surface thereof (in a direction tangent to the surface thereof if the sheet is curved). Some sheet feeders can rotate a sheet about an axis parallel to a direction normal to the surface of the sheet. A first example of such sheet feeders feeds and rotates a sheet before image formation with an image-forming unit, as proposed in Japanese Patent Nos. 3120896 and 3149139. A second example rotates a sheet after image formation, as proposed in Japanese Patent Laid-Open Nos. 2002-234636 and 9-40230.
The sheet feeders of the known art are advantageous to some degree in terms of the size reduction of the entire apparatus and the increase in processing speed. These sheet feeders, however, require an additional sheet-rotating mechanism and a drive unit therefor which considerably complicate the structures and control systems of the sheet feeders.